Ultracentrifugal Determination of Molecular Weights of Small Molecules by the Archibald Procedure1

1954 ◽  
Vol 76 (12) ◽  
pp. 3342-3344 ◽  
Author(s):  
Raymond A. Brown ◽  
David Kritchevsky ◽  
Maurice Davies
Keyword(s):  
Small Molecules ◽  
Molecular Weights

Determination of the Molecular Weights and the Structures of Rubber, Gutta-Percha and Balata. Communication No. 258 on Macromolecular Compounds. Communication No. 49 on Isoprene and Rubber

1942 ◽  
Vol 15 (3) ◽  
pp. 473-522
Author(s):  
H. Staudinger ◽  
Kl Fischer
Keyword(s):  
Small Molecules ◽  
Colloidal Particles ◽  
High Viscosity ◽  
Molecular State ◽  
Colloidal Solutions ◽  
Great Tendency ◽  
Molecular Weights ◽  
Gutta Percha ◽  
Long Time

Abstract The method used to determine the constitutions of rubber, gutta-percha and balata is essentially the same as that used for organic substances of low molecular weights, i.e., the substance is dissolved in a solvent, and the size and character of the particles in solution are determined. For a long time the nature of colloidal solutions of these hydrocarbons was in dispute. Up to twenty years ago, it was commonly assumed that the molecules of these hydrocarbons are relatively small, and that their colloidal particles are formed by the assemblage of small molecules into micelles through the agency of secondary forces. It seemed to Pummerer, Nielsen and Gündel that in certain solvents, such as camphor and menthol, rubber is dissolved in a low-molecular state. Subsequently, however, this observation was proved to be incorrect. According to the opinion of Meyer and Mark, colloidal particles of rubber are composed of relatively long primary-valence chains, which contain from 75–150 isoprene residues. These chains are, in turn, assembled into micelles by “micellar forces.” The authors explain this in the following way: “The high viscosity of rubber solutions, e.g., in benzene, would lead one to conclude that very large, highly solvated micelles are present in these solvents.” At the time, this hypothesis seemed to explain quite satisfactorily the nature of rubber and its solutions, for the great tendency of these solutions to undergo certain changes on standing, which are manifest by an increase or decrease in viscosity, is readily comprehensible on this basis.

Transmission Electron Microscopy of Protein Macromolecules

1971 ◽  
Vol 29 ◽  
pp. 424-425
Author(s):  
Henry S. Slayter
Keyword(s):  
Biological Systems ◽  
Metal Vapor ◽  
Resolving Power ◽  
Electron Microscopic ◽  
Chemical Methods ◽  
Molecular Weights ◽  
The Past ◽  
Physical Chemical ◽  
Transmission Electron

Electron microscopic methods have been applied increasingly during the past fifteen years, to problems in structural molecular biology. Used in conjunction with physical chemical methods and/or Fourier methods of analysis, they constitute powerful tools for determining sizes, shapes and modes of aggregation of biopolymers with molecular weights greater than 50, 000. However, the application of the e.m. to the determination of very fine structure approaching the limit of instrumental resolving power in biological systems has not been productive, due to various difficulties such as the destructive effects of dehydration, damage to the specimen by the electron beam, and lack of adequate and specific contrast. One of the most satisfactory methods for contrasting individual macromolecules involves the deposition of heavy metal vapor upon the specimen. We have investigated this process, and present here what we believe to be the more important considerations for optimizing it. Results of the application of these methods to several biological systems including muscle proteins, fibrinogen, ribosomes and chromatin will be discussed.

Preparation of graft copolymers by the reaction of polymeric acyl chlorides with monohydroxy-terminated polymers: An introductory study

1988 ◽  
Vol 53 (8) ◽  
pp. 1735-1744 ◽  
Author(s):  
Jitka Horská ◽  
Jaroslav Stejskal ◽  
Pavel Kratochvíl ◽  
Aubrey D. Jenkins ◽  
Eugenia Tsartolia ◽  
...  
Keyword(s):  
Light Scattering ◽  
Chemical Composition ◽  
Statistical Model ◽  
Graft Copolymers ◽  
Coupling Reaction ◽  
Molecular Characteristics ◽  
Gel Formation ◽  
Acyl Chlorides ◽  
Molecular Weights

An attempt was made to prepare well-defined graft copolymers by the coupling reaction between acyl chloride groups located along the backbone chain and monohydroxy-terminated grafts prepared separately. The molecular weights and the parameters of heterogeneity in chemical composition of the products were determined by light scattering and osmometry. The determination of molecular characteristics revealed that the degree of grafting was low. The results therefore could not be confronted with a statistical model at this stage. The problems encountered in the synthesis, e.g., gel formation, and the data relating to the soluble products are discussed.

Determination of molecular weights by the archibald method using absorption optics

1969 ◽  
Vol 30 (2) ◽  
pp. 212-216 ◽  
Author(s):  
K. de Groot ◽  
J.C.M. Reijnen ◽  
H.J. Hoenders
Keyword(s):  
Molecular Weights

Determination of Molecular Weights of Polysaccharides by Over-oxidation with Periodate

Nature ◽  
1959 ◽  
Vol 183 (4666) ◽  
pp. 991-992 ◽  
Author(s):  
F. W. PARRISH ◽  
W. J. WHELAN
Keyword(s):  
Molecular Weights

Determination of the Molecular Weights of Oils

1939 ◽  
Vol 11 (8) ◽  
pp. 440-442 ◽  
Author(s):  
William E. Hanson ◽  
John R. Bowman
Keyword(s):  
Molecular Weights
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